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Thu, 8 Oct 2026 07:44:05 +0000 (UTC) Received: from warthog.com (unknown [10.44.32.90]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id F29A11956086; Thu, 8 Oct 2026 07:43:58 +0000 (UTC) From: David Howells To: Christian Brauner Cc: David Howells , Paulo Alcantara , Matthew Wilcox , Namjae Jeon , Marc Dionne , Stefan Metzmacher , Eric Van Hensbergen , Dominique Martinet , Ilya Dryomov , netfs@lists.linux.dev, linux-afs@lists.infradead.org, linux-cifs@vger.kernel.org, linux-nfs@vger.kernel.org, ceph-devel@vger.kernel.org, v9fs@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH v15 1/8] mm: Make readahead store folio count in readahead_control Date: Thu, 8 Oct 2026 08:43:37 +0100 Message-ID: <20261008074346.936909-2-dhowells@redhat.com> In-Reply-To: <20261008074346.936909-1-dhowells@redhat.com> References: <20261008074346.936909-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Mimecast-MFC-PROC-ID: ZAD8r0vNosZ5T3sG8Ut-v7coJ3aeJgRV7gvyv0zwuqI_1791445446 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: 8bit content-type: text/plain; charset="US-ASCII"; x-default=true X-Rspamd-Queue-Id: 71D4D40002 X-Rspam-User: X-Rspamd-Server: rspam12 X-Stat-Signature: tyr5aymzmhx8e1m1mtsowf6hdnjmywe5 X-HE-Tag: 1791445452-770590 X-HE-Meta: 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 FGYUwnNx 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Make readahead store folio count in readahead_control so that the filesystem can know in advance how many folios it needs to keep track of. This is cleared by read_pages() in case it is called from a loop. The count is accessed by the filesystem with readahead_folio_count(). Signed-off-by: David Howells Reviewed-by: Paulo Alcantara (Red Hat) cc: Matthew Wilcox cc: netfs@lists.linux.dev cc: linux-mm@kvack.org cc: linux-fsdevel@vger.kernel.org --- include/linux/pagemap.h | 10 ++++++++++ mm/readahead.c | 5 +++++ 2 files changed, 15 insertions(+) diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 0adfa6605653..b7154b81d0d7 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -1411,6 +1411,7 @@ struct readahead_control { struct file_ra_state *ra; /* private: use the readahead_* accessors instead */ pgoff_t _index; + unsigned int _nr_folios; unsigned int _nr_pages; unsigned int _batch_count; bool dropbehind; @@ -1590,6 +1591,15 @@ static inline size_t readahead_batch_length(const struct readahead_control *rac) return rac->_batch_count * PAGE_SIZE; } +/** + * readahead_folio_count - Get the number of folios in this readahead request. + * @rac: The readahead request. + */ +static inline unsigned int readahead_folio_count(const struct readahead_control *rac) +{ + return rac->_nr_folios; +} + static inline unsigned long dir_pages(const struct inode *inode) { return (unsigned long)(inode->i_size + PAGE_SIZE - 1) >> diff --git a/mm/readahead.c b/mm/readahead.c index 6e5563290287..196542fb1c93 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -188,6 +188,7 @@ static void read_pages(struct readahead_control *rac) if (unlikely(rac->_workingset)) psi_memstall_leave(&rac->_pflags); rac->_workingset = false; + rac->_nr_folios = 0; BUG_ON(readahead_count(rac)); } @@ -303,6 +304,7 @@ void page_cache_ra_unbounded(struct readahead_control *ractl, if (i == mark) folio_set_readahead(folio); ractl->_workingset |= folio_test_workingset(folio); + ractl->_nr_folios++; ractl->_nr_pages += min_nrpages; i += min_nrpages; } @@ -473,6 +475,7 @@ static inline int ra_alloc_folio(struct readahead_control *ractl, pgoff_t index, return err; } + ractl->_nr_folios++; ractl->_nr_pages += 1UL << order; ractl->_workingset |= folio_test_workingset(folio); return 0; @@ -822,6 +825,7 @@ void readahead_expand(struct readahead_control *ractl, ractl->_workingset = true; psi_memstall_enter(&ractl->_pflags); } + ractl->_nr_folios++; ractl->_nr_pages += min_nrpages; ractl->_index = folio->index; } @@ -851,6 +855,7 @@ void readahead_expand(struct readahead_control *ractl, ractl->_workingset = true; psi_memstall_enter(&ractl->_pflags); } + ractl->_nr_folios++; ractl->_nr_pages += min_nrpages; if (ra) { ra->size += min_nrpages;